In multi-user environments, it may be desirable for multiple users be able to edit the same document at the same time. Often, when multiple users are editing the document, confusion can exist as to how the various edits are added to the document. For example, sometimes multiple versions of the document are edited, making it difficult to merge the edits into a single, complete document.
Even in systems that support multi-user editing of a document, users typically cannot control when the users' edits are shown to others editing the document. Further, it can be difficult to define which user is working on which particular part of the document, thereby resulting in possible conflicts in the changes made to the document.